Furnace for heating lens blanks



Nov. 13, 1945.

H. c. WELJTER 2,388,888

FURNACE FOR HEATING LENS BLANKS Filed NOY. 25, 1942 Gttomeg l Patented Nov. 13, 1945 UNITED STATESv PATENT OFFICE 1 f' E j' 2,888,888

, FURNAC FOR HEATING LENS BLANKS Harvey "C, WellerQ'Tole'do, ,0hio, aussignor to SurfaceCombustion Corporation, Toledo, Ohio, a @samenwer I' .y yApplication November 25,1942, SeralNo. 466,933

s claims. (C1, 268-43) invention relatesv to the fart `of heating relatively small lens blanksrto molding tempera-V ture andthe object vof the invention'is tcl-provide arelativelysimple .and practical-gas red furnace wherein the heating operation may be conducted. Y i A Inthe accompanyingV drawing forming part of this specification, I

Fig..1.isfa.partial front elevation and vertical sectionof the improved furnace, the section being taken on 1ine.iI-I of Fig. 2;

Fig.,2 is a vertical section on line 2 2 1; and f Fig. 3 is a horizontal section on 3-3 ofFig. l.

The. furnace ofthe present invention is supported on a stand 5 and comprises a bottom wallv 6; lateral side wallsl 'and 8; a roof 9; a back wall I0, and a front wall II having a doors opening I2, all made of the usual fire brick within a steel casing of whichvthe bottom is indicated at 6. The. space between the side walls is divided by two upright heat permeable refractory walls of Fig.

I3 and I4 into a rcentral heating' chamber I5v wherein the lens blanks (hereinafter sometimes called Ywork-f) will be'placed for heating to molding temperature and two similar left and right hand hot-gas or ring chambers'l and II.v A

refractory lslab I8 supported on thebottom wall 6 between walls I3 andi!! constitutes the hearth ofthe heating chamber. .Y

Twosimilarburners I9 andIZU-re upwardly into theright hand firingl chamber I'I and a single similarburnerV 2| fires upwardly into the left hand'ringchamber I6. Therefore; when the same amount of fuel .is supplied to veach of the burners'the right hand side of the heating chamber I5 will be at a substantially highertemperature-'than theleft hand side thereof. The burner. for the left hand firing chamber I6 vis positioned closer to the back wall of that chamber thanxto the front wall thereof and conse- Asages. is provided with a multiplicity of relatively small gas discharge ports I4', three verticallyspaced 4' rows of such ports being shown. IHet gases in quently theback portion of theheat permeable wall YI3 :will be more highly heated than theportion next to the door opening I2. i

The vburners' are of a type adapted to burn a preformed mixture of air and gas, each burner comprising a refractory tunnel 22 to which the combustible mixture is delivered from a suitable source of supply shown as comprising for each burner a mixing tube .23 into the lower end of which a jet of gas is discharged from a supply pipe 24 in a manner to entrain the combustion supporting air,V each supply pipe being shown as proyided with a manually adjustable gas valve is shown as housed in a square refractory block 21 the lower end of whichv is seated on a metal plate 28 adapted to be detachably secured'to side brackets 29 which depend from the bottom wall '..6' of the furnace casing.

The right hand side of the door opening :I2 is i preferably some distancefto the left of the right hand heat permeable wall I4 as indicated byth'e front wall extension II whereas the left hand 'side of said opening is preferably in the same vertical plane as the adjacent face of the' heat permeable wall I3, it being understood thatY the extension II' serves to prevent the vadjacent edge Illa, respectively, between vthe respective ring chambers I6 and I'I and the heating chamber I5, fit being understood that in the absence of other exit openings from the said firing chambers, all of the hot gases from rthe firing chambers would enter the heating chamber by way of said pasr The right hand heat permeablewall I4 the chamber I 'I will, therefore, flow into the uheating chamber I5 not only by way of the top vection as well as by radiation from the heat permeable wall I4.

discharge ports I3' so that hot gases 'in the left hand ring chamber I5 may also flow into the heating chamber I5 by way of said ports. kHOW- everit Will be readily appreciated that inasmuch as the left hand ring chamber I6 is fired by`a single burner the pressure of the hot gases in that chamber will be less than the pressure of the same in the right hand firing chamber with the result that the velocity of the gases entering the heating chamber from the left hand chamber I6 will be less than those entering from the right hand ring chamber II;

In front of the furnace at the left hand side thereof is a vertically Aadjustable shelf 3B which will normallybev so adjusted that it will be at the same level as vthe top ofthe hearth I 8, 1t being noted thatgthe right hand end of the shelf is some distance to the rightof the left hand 25, andapressuregauge 26.. l. The burner tunnel 55 side of the door opening I2. The purpose of this.

The left hand heat permeable wall I3 is pref-v erably also provided with a multiplicity of gas shelf is to allow the operator to place the lens blanks on the shelf preparatory to placing them in the heating chamber as by tongs.I The left hand front end of the heating chamber adjacent the door opening will be relatively cool as compared with the back left hand corner thereof and, therefore, by introducing the blank at the left hand front `end vof the .heating chamber. and gradually movingfit towards the lefthand corner, the blank will gradually be exposed to higher temperatures. Eventually, the operator will move the blank over towards the hotter right hand side of the heating chamber Yorto -any desired point between the two heat permeable walls I3 'and I4 as may be necessary ,to insure that theV blanks will be at the proper temperature before they are removed from the heating chamber for molding in a machine not shown. Y e

After the lens blanks have been moldehthey must be annealed in annealing apparatus not shown. However, inasmuch as Vthe blanks are relatively small,.the .usual procedure is not to anneal them .until a considerable vnumber of blanks have been accumulated. In the meantime, it is desirable that theimolded blanks be kept warm orfairly hot and 'to this end there is provided'on top of the furnace an'oven 3l which is kept suiciently hot by allowing hot gases from the heating chamber to flowlthereinto as by way of one or more upright passages 32 in the roof 9 of the heating chamber.

In order to protect the operator from hot gases owing out of the heating chamber by way .of the front door opening I2 thereof, there may be provided in front of the door opening a shield 34 for diverting the gases upwardly (see Fig. 2), the shield ordinarily being made of some transparent material so that the operator can look through the same into the `heating chamber to facilitate his manipulation of the lens blanks.

The hearth I8 of the heating chamber is preferably removably supported on the iioor of the furnace so that it can be readily withdrawn by pulling the same horizontally outward through the door opening I2, the front wall extension II having a side notch indicated by the `dotted line I Ia to permit such withdrawal.

Both of the heat permeable walls I3 and I4 are preferably supported in a manner to permit their ready removal in case they require replacement for one cause or another. To this end each wall is detachably seated on the bottom wall of the furnace and is held in an upright position in any preferred way as by a notched brick 33 whichabuts the same, the brick being removably positioned in the back wall 'Ill of the furnace for withdrawal from the outside of the furnace. i

Although some parts of the furnace have been described in greater detail than other parts, it

tended except as expressed in the appended claims.

What is claimed is:

1. In a furnace for the purpose described, the combination of aback wall, two laterally spaced walls extending forwardly in front of said back wall, said back wall and side walls vconstituting three side walls of a heating chamber, aV roof above said heating chamber, arid'h'ot gas chambers, one each being located at either side of said whereby hot gases from said hot gas chambers may pass over said side walls and through said apertures to said heating chamber.

2. In a heat treating furnace, the combination of a chambered structure comprised of a bottom wall, a back wall, a front wall, a pair of end walls and a roof, a pair of walls extending upwardly from the bottomwall and betweenthe front and back walls for dividingthe space between the said end walls into a middle and two end compartments, and a hearth in the middle compartment and the latter having a frontL opening ,through which-access can be had to material on the hearth, each of said pair of walls being provided'with a plurality of apertures therethrough and having a passageway over the top thereof, whereby ported communication is possible from said end compartments to said middle compartment for the passage of hot gases.

3. Ina heat treating furnace, the combination of achambered structure comprised of a bottom l wall, a back wall, a front wail, a pair of end will be understood that no limitations are interminating in spaced relation .from said roof,

walls and a roof, a. pair of walls extending upwardly from the bottom wall and between the Y front and back walls `for dividing the .space between the said end walls into a middle and twol end compartments, a hearth in the middle compartment and the latter having a front opening through which access can be had to material on the hearth, each of said pair of walls being provided with a plurality of apertures therethrough,

whereby ported communication is possible from said end compartments to said middle compart-t ment for thepassage of hot gases. means for providing hot gases and discharging into a rst one of said end compartments at a location toward the rear thereof, and means for providing hot gases and discharging the same into the second of said 'end compartments at locations both at the front and at the rear thereof.

4. In a heat treatingfurnace, the combination ofa chambered structure comprised of a bottom wall, a back wall, -a front wall, a pair of end walls and a roof, a pair of walls extending up# wardly from the bottom wall and between the front and back walls fordividing the spacebetween the said end walls into a middle and two end compartments, a hearth in the middle compartment and thev Vlatter having a front opening Vthrough which access can be had to` material on the hearth, each of said pair of `walls being provided with a plurality of apertures therethrough, whereby ported communication is possible from said endv compartments to said middle compart-V ment for the passage of hot gases, means for supplying hot gases to the rear of a rst one of said end compartments while leaving the front portion relatively cool, and separate means for supplying hot gasesto both the front and rear portions to the second of said end compartments.

5. In a lheat treating furnace, the combination of a chambered structure .comprised of a bottom wall, a back wall, a front wall, a pair of end walls and a roof, a pair of walls extending lupwardly from the bottom wall and between the front and back walls for vdividing the space between the said end walls into a middle and two end compartments, av hearth in the middle compartment and the latter having a front opening through which access can be had to material on the hearth, each of said pair of walls being provided with a plurality of apertures therethrough, whereby ported communication is possible from .said end vcornpartments to said middle compartment for thev passage of hot gases, means for-providinghot gases and discharging the same into a rst of said end compartments, and means for providing hot gases and discharging them into the second of said end compartments, said latter means being capable of supplying an amount of gas in multiple of that supplied to the rst said end compartment. A

6. In a heat treating furnace, the combination of a chambered structure comprised of a bottom wall, a back wall, a front wall, a pair of end walls and a roof, a pair of Walls extending upwardly from the bottom wall and between the front and 'back walls for dividing the space between the said end Walls into a middle and two end compartments, and a hearth in the middle compartment and the latter having a front opening through which access can be had to material on the hearth, each of said pair of walls being provided with a plurality of apertures therethrough and having a passageway over the top thereof,

whereby ported communication is possible from which said rst mentioned portion of the front wall extends.

HARVEY C. WELLER. 

